Digi Embedded Linux is NOT a Real Time OS and you cannot expect any kind of determinism.
A non-modified kernel (without Real Time extensions ported to it) will NOT guarantee to achieve the time requirement if has to be deterministic.
It may be between the margins most of the time, but will not be deterministic. Which means if the CPU becomes busy it may miss the target window.
In some applications it is ok if it is on time most of the time but not always, in some it is not ok and DEL should not be used in those cases.
First you can implement your application as is and see if you get a satisfactory result. If not you'd have to consider porting Real Time extensions to kernel.
or you can hire Digi consulting group to do this for you as they had done this before for other customers on other platforms.